Process To Prepare a Mineral Derived Residual Deasphalted Oil Blend

ABSTRACT

The invention relates to a process to prepare an oil blend comprising: (i) de-asphalting a mineral-derived vacuum residue to obtain a de-asphalted oil, (ii) optionally extracting from the de-asphalted oil an aromatic extract by solvent extraction process; and (iii) blending the de-asphalted oil obtained in (i) or the aromatic extract obtained in (ii) with a paraffin base oil. The invention further relates to the oil blends obtainable by the process, and their uses.

The present invention relates to a process to prepare a blend of a mineral derived residual and de-asphalted oil component, the blend as obtainable, a cylinder oil composition comprising said oil blend, and to the use of the oil blend as a process oil for various processes.

GB-A-1496045 describes a process to prepare high viscosity base oils wherein a vacuum residue of a crude petroleum source is first subjected to a propane de-asphalting step to obtain a de-asphalted oil (DAO). The DAO is further subjected to a furfural extraction process in order to extract de-asphalted cylinder oil (DACO) therefrom. The DACO is the extracted material obtained after removal of the extraction solvent, and contains the polycyclic compounds which are undesirable in bright stock oil because of their low viscosity index and low oxidative stability.

U.S. Pat. No. 4,592,832 discloses a process to prepare a bright stock oil having a kinematic viscosity at 100° C. of 37 mm²/sec and a viscosity index of 95 as prepared from a light Arabian Vacuum Resid. The light Arabian Vacuum Resid is subjected to a propane de-asphalting step to prepare a DAO. The DAO is subjected to a N-methyl-pyrrolidone (NMP) solvent extraction step followed by de-waxing to obtain the bright stock oil, while the aromatic extract (also referred to as DACO, de-asphalted cylinder oil) is recycled to the solvent extraction step, or eventually sent to a cat cracker unit.

Bright stock oil is commonly used as a base oil in lubricating oil compositions, in particular in lubricating oil compositions for marine and stationary low-speed crosshead diesel engines burning residual fuels with sulphur contents of up to 4.0 wt. % and for trunk piston, medium-speed diesel engines operating on residual fuel in industrial and marine applications. For instance US-A-2003/0100453 discloses a blend of a Group I or Group V mineral derived base oil and Fischer Tropsch derived base oil. The Group I or Group V mineral derived base oils can be understood to comprise bright stock oils. The blend is reported to exhibit a better Oxidator A stability than the Fischer Tropsch oil, and a better Oxidator BN stability test than the Group I or V mineral derived base oil. A disadvantage of this blend is that solely lube oils can be formulated that nave a medium to low viscosity, which renders the blends unsuitable for e.g. Marine cycle oil applications.

It will be appreciated in the art that the term “marine” does not restrict such engines to those used in water-borne vessels. That is to say, in addition said term also includes engines used for power generation applications. These highly rated, fuel efficient, low-speed marine and stationary diesel engines operate at high pressures, high temperatures and long strokes.

Furthermore, the above-described processes steps required to prepare a bright stock are complex, and make it difficult to obtain a base oil having a combination of a high viscosity, good solubility and a medium viscosity index. This can be explained by the fact that the aromatic compounds as present in the DAO have a negative contribution to the viscosity index and have a relatively high viscosity whereas the saturates components have a lower viscosity contribution and variable VI contribution. Thus by removing these aromatic compounds in the solvent extraction step the viscosity index improves at the expense of the viscosity.

Furthermore, the removal of the aromatic compounds decreases the volatility of the oil component at a given viscosity, which is undesired when the oil component is to be employed as a all-loss lubricant. Yet further, the overall yield of usable lubricant or process oils is reduced strongly, which is highly undesired in view of diminishing occurrence of paraffinic base crude oils.

An object of the present invention is to provide a blend of a mineral-derived residual and de-asphalted oil component base oil, which has a low pour point, a medium viscosity index and a high viscosity.

Accordingly, in the present invention there is provided a process to prepare an oil blend comprising:

(i) de-asphalting a mineral-derived vacuum residue to obtain a de-asphalted oil, (ii) optionally extracting from the de-asphalted oil an aromatic extract by solvent extraction process; and (iii) blending the de-asphalted oil obtained in (i) or the aromatic extract obtained in (ii) with a paraffin base oil.

In a further embodiment of the present invention there is provided an oil blend comprising (A) paraffinic base oil component and (B) a mineral derived residual and de-asphalted oil or de-asphalted oil cylinder oil in an amount of from 40 to 95 wt. %, based on the total amount of the oil blend.

The present invention further provides for the use of the oil composition as a cylinder oil lubricant for cross-head engines or a trunk piston engine oil, such as medium-speed industrial or marine propulsion and auxiliary engines burning residual fuel oils.

Furthermore, the present invention also provides a cylinder oil composition comprising the oil blend and one or more additives selected from dispersants, detergents, antiwear agents, friction reducing agents, viscosity thickeners, metal passivators, acid sequestering agents, pour point depressants, corrosion inhibitors, defoaming agents, seal fix or seal compatibility agents and antioxidants.

In yet a further aspect, the invention is directed at the use of the blends as alternatives for various existing process oils such as TDAE (treated distillate aromatic extract), naphthenic and paraffinic process oils. These blends can be widely used as extender oil in rubber formulations (e.g. tyres and other automotive and technical rubber articles), rubber mould articles and seals. In yet a further aspect, the invention is directed at shaped articles comprising the oil blends. Furthermore, the present invention also provides for use of the oil blends as kneader oil in bunberry mixers, as carrier oil in printing inks, and as carrier oil for additives, as a sand binder for metal casting, as a process oil in the production of carbon black for printing inks, as a process oil in electrical wire and cable insulating materials, and as dust binder.

It has been surprisingly found that medium viscosity index base oil blends are possible if a paraffin base oil is blended with a de-asphalted oil or a de-asphalted cylinder oil.

The oil blend preferably has a kinematic viscosity at 100° C. of greater than 25 mm²/sec. Preferably said viscosity is less than 50 mm²/sec. The viscosity index of the blend is preferably greater than 50 and more preferably between 60 and 95. This oil blend is very attractive because its components are easily derivable. It was found that a de-asphalted oil component as present in this blend can be used which has not been subjected to a solvent extraction process or at least not to a very severe solvent extraction process. Thus the de-asphalted oil component of the blend can be prepared more simply than when using the process of GB-A-1496045. It was found that by blending a substantially paraffinic base oil to said component the solvent extraction cold be reduced or even omitted resulting in a highly viscous oil blend having also a high viscosity index for these type of products.

The mineral derived residual and de-asphalted oil component is defined as the product of a de-asphalting process step wherein asphalt is removed from a reduced crude petroleum feed or from the residue, bottom fraction, of a vacuum distillation of a crude petroleum feed. The de-asphalting process utilizes a light hydrocarbon liquid solvent, for example propane, for asphalt compounds. De-asphalting processes are well known and for example described in Lubricant base oil and wax processing, Avilino Sequeira, Jr., Marcel Dekker, Inc, New York, 1994, ISBN 0-8247-9256-4, pages 53-80. The mineral derived residual and de-asphalted oil component as used in the blend according to the invention may be the DAO product as directly obtained in said de-asphalting process. Alternatively, the mineral derived residual and de-asphalted component may also be the aromatic extract as isolated from said de-asphalted component by solvent extraction in the case of applications where high oxidative stability is not required.

The DAO product may be subjected to a mild solvent extraction process in order to remove some of the aromatic compounds. It has been found that when the polar compounds content of resultant, optionally dewaxed, mineral derived residual and de-asphalted oil component is suitably between 60 and 80 wt % by IP 368, a solvent extraction can be omitted. The content of polar compounds in the oil blend is preferably below 60 wt % by IP 368. Because a relatively high content of polar compounds may be present in this mineral oil component: a relatively high viscosity of said oil is achievable. Preferably the kinematic viscosity at 100° C. of said oil is between 40 and 55 mm²/sec. The viscosity index of the mineral derived residual and de-asphalted oil component may be as high as between 70 and 85. In a preferred embodiment the mineral derived residual and de-asphalted oil component is a solvent dewaxed DAO which oil has not been subjected to a solvent extraction process. When reference is made to solvent extraction process, processes like for example the furfural or NMP solvent extraction processes are meant or other solvent extraction processes as for example described in Chapter 5 of the above referred to textbook titled “Lubricant base oil and wax processing”.

The paraffinic base oil component preferably has a viscosity index of between 125 and 180. The kinematic viscosity at 100° C. of the paraffinic base oil is preferably greater than 2 mm²/sec, more preferably greater than 3 mm²/sec, again more preferably greater than 4 mm²/sec, yet more preferably greater than 8 mm²/sec, and again more preferably greater than 12 mm²/sec, and further preferably greater than 15 mm²/sec at 100° C. The combination of viscosity index and viscosity are typical for the preferred paraffin base oil and differentiates the paraffin base oil from the naphthenic base oil having much lower value for VI in this viscosity range. There is no preferred upper limit for the viscosity. However applicant found that a paraffin base oil as derived from a Fischer-Tropsch wax having a kinematic viscosity at 100° C. of between 12 and 25 mm²/sec and more preferably between 153 and 25 mm²/sec can be used advantageously as paraffin base oil component. The pour point of the paraffin base oil is preferably below 0° C., more preferably below −9° C. The pour point will suitably be above −50° C.

The paraffin base oil may be prepared by oligomerisation of lower molecular weight olefins to iso-paraffins having the desired viscosity as for example described in US-A 20040178118. More preferably the paraffin base oil is prepared by hydroisomerisation of a paraffin wax, as prepared in a Fischer-Tropsch synthesis step, and dewaxing a residual fraction as separated from the effluent of said hydroisomerisation process. Examples of such processes suitable for preparing the paraffin base oils are described in WO-A-2004/00-7647, US-A-US2004/0065588, WO-A-2004/033595 and WO-A-02070627, which publications are hereby incorporated by reference. Mixtures of the paraffin base oils as prepared by these two processes may also be suitably used as the paraffin base oil. Such mixtures are illustrated in the above referred to US-A-20040178118. A disadvantage of the process of US-A-20040178118 is that in order to achieve a high viscosity for the desired paraffin base oil first two base oils must be prepared having a low and high viscosity by two different processes. More preferred is to prepare the paraffin base oil in a single process involving hydroisomerisation of a relatively heavy paraffin wax, as prepared in a Fischer-Tropsch synthesis step, and dewaxing a residual fraction as separated from the effluent of said hydroisomerisation process.

This relatively heavy feed to the hydroisomerisating step has suitably a weight ratio of compounds having at least 60 or more carbon atoms and compounds having at least 30 carbon atoms of at least 0.2, preferably at least 0.4 and more preferably at least 0.55. Furthermore the feed has at least 30 wt %, preferably at least 50 wt % and more preferably at least 55 wt % of compounds having at least 30 carbon atoms. Such a feed preferably comprises a Fischer-Tropsch product, which in turn comprises a C₂₀+ fraction having an ASF-alpha value (Anderson-Schulz-Flory chain growth factor) of at least 0.925, preferably at least 0.935, more preferably at least 0.945, even more preferably at least 0.955. The initial boiling point of the feed is preferably below 200° C. Preferably any compounds having 4 or less carbon atoms and any compounds having a boiling point in that range are not present in said feed. The feed may also comprise process recycles and/or off-spec base oil fractions as obtained after dewaxing.

A suitable Fischer-Tropsch synthesis process, which may yield a relatively heavy Fischer-Troosch product, is for example described in WO-A-9934917.

The process will generally comprise a Fischer-Tropsch synthesis to obtain a Fischer-Tropsch wax, a hydroisomerisation step and a pour point reducing step of a residual fraction, comprising

(a) hydrocracking/hydroisomerisating a Fischer-Tropsch wax, (b) separating from the product of step a) a distillation residue and (c) dewaxing the distillation residue to obtain the paraffin base oil and an optionally. (d) a re-distillation of the paraffin base oil to remove light ends such to obtain a residual paraffinic base oil having the desired viscosity.

The hydroconversion/hydroisomerisation reaction of step (a) is preferably performed in the presence of hydrogen and a catalyst, which catalyst can be chosen from those known to one skilled in the art as being suitable for this reaction of which some will be described in more detail below. The catalyst may in principle be any catalyst known in the art to be suitable for isomerising paraffinic molecules. In general, suitable hydroconversion/hydroisomerisation catalysts are those comprising a hydrogenation component supported on a refractory oxide carrier, such as amorphous silica-alumina (ASA), alumina, fluorided alumina, molecular sieves (zeolites) or mixtures of two or more of these. One type of preferred catalysts to be applied in the hydroconversion/hydroisomerisation step in accordance with the present invention are hydroconversion/hydroisomerisation catalysts comprising platinum and/or palladium as the hydrogenation component. A very much preferred hydroconversion/hydroisomerisation catalyst comprises platinum and palladium supported on an amorphous silica-alumina (ASA) carrier. The platinum and/or palladium is suitably present in an amount of from 0.1 to 5.0% by weight, more suitably from 0.2 to 2.0% by weight, calculated as element and based on total weight of carrier. If both present, the weight ratio of platinum to palladium may vary within wide limits, but suitably is in the range of from 0.05 to 10, more suitably 0.1 to 5. Examples of suitable noble metal on ASA (catalysts are, for instance, disclosed in WO-A-9410264 and EP-A-0582347. Other suitable noble metal-based catalysts, such as platinum on a fluorided alumina carrier, are disclosed in e.g. U.S. Pat. No. 5,059,299 and WO-A-9220759.

A second type of suitable hydroconversion/hydroisomerisation catalysts are those comprising at least one Group VIB metal, preferably tungsten and/or molybdenum, and at least one non-noble Group VIII metal, preferably nickel and/or cobalt, as the hydrogenation component. Both metals may be present as oxides, sulphides or a combination thereof. The (Group VIB metal is suitably present in an amount of from 1 to 35% by weight, more suitably from 5 to 30% by weight, calculated as element and based on total weight of the carrier. The non-noble Group VIII metal is suitably present in an amount of from 1 to 25 wt %, preferably 2 to 15 wt %, calculated as element and based on total weight of carrier. A hydroconversion catalyst of this type, which has been found particularly suitable, is a catalyst comprising nickel and tungsten supported on fluorided alumina.

The above non-noble metal-based catalysts are preferably used in their sulphided form. In order to maintain the sulphided form of the catalyst during use some sulphur needs to be present in the feed. Preferably at least 10 mg/kg and more preferably between 50 and 150 mg/kg of sulphur is present in the feed.

A preferred catalyst, which can be used in a non-sulphided form, comprises a non-noble Group VIII metal, e.g., iron, nickel, in conjunction with a Group IB metal, e.g., copper, supported on an acidic support. Copper is preferably present to suppress hydrogenolysis of paraffins to methane. The catalyst has a pore volume preferably in the range of 0.35 to 1.10 nl/g as determined by water absorption, a surfaces area of preferably between 200-500 m²/g as determined by BET nitrogen adsorption, and a bulk density of between 0.4-1.0 g/ml. The catalyst support is preferably made of an amorphous silica-alumina wherein the alumina may be present within wide range of between 5 and 96 wt %, preferably between 20 and 85 wt %. The silica content as SiO2 is preferably between 15 and 80 wt %. Also, the support may contain small amounts, e.g., 20-30 wt %, of a binder, e.g., alumina, silica, Group IVA metal oxides, and various types of clays, magnesia, etc., preferably alumina or silica.

The preparation of amorphous silica-alumina microspheres has been described in Ryland, Lloyd B., Tamele, M. W., and Wilson, J. N., Cracking Catalysts, Catalysis: volume VII, Ed. Paul H. Emmett, Reinhold Publishing Corporation, New York, 1960, pp. 5-9.

The catalyst is prepared by co-impregnating the metals from solutions onto the support, drying at 100-150° C., and calcining in air at 200-550° C. The Group VIII metal is present in amounts of about 15 wt % or less, preferably 1-12 wt %, while the Group IB metal is usually present in lesser amounts, e.g., 1:2 to about 1:20 weight ratio respecting the Group VIII metal.

A typical catalyst is shown below:

Ni, wt % 2.5-3.5 Cu, wt % 0.25-0.35 Al₂O₃—SiO₂ wt % 65-75 Al₂O₃ (binder) wt % 25-30 Surface Area 290-325 m²/g Pore Volume (Hg) 0.35-0.45 ml/g Bulk Density 0.58-0.68 g/ml

Another class of suitable hydroconversion/hydroisomerisation catalysts are those based on zeolitic materials, suitably comprising at least one Group VIII metal component, preferably Pt and/or Pd, as the hydrogenation component. Suitable zeolitic and other aluminosilicate materials, then, include Zeolite beta, Zeolite Y, Ultra Stable Y, ZSM-5, ZSM-12, ZSM-22, ZSM-23, ZSM-48, MCM-68, ZSM-35, SSZ-32, ferrierie, mordenite and silica-aluminophosphates, such as SAPO-11 and SAPO-31. Examples of suitable hydroisomerisation/hydroisomerisation catalysts are, for instance, described in WO-A-9201657. Combinations of these catalysts are also possible. Very suitable hydroconversion/hydroisomerisation processes are those involving a first step wherein a zeolite beta based catalyst is used and a second step wherein a ZSM-5, ZSM-12, ZSM-22, ZSM-23, ZSM-48, MCM-68, ZSM-35, SSZ-32, ferrierite, mordenite based catalyst is used. Of the latter group ZSM-23, ZSM-22 and ZSM-48 are preferred. Examples of such processes are described in US-A-2004/0065581 and US-A-2004/0065588. In the process of US-A-2004/0065588 steps (a) and (c) as meant in the context of the present description are performed using the same ZSM-48 based catalyst.

Combinations wherein the Fischer-Tropsch product is first subjected to a first hydroisomerisation step using the amorphous catalyst comprising a silica-alumina carrier as described above followed by a second hydroisomerisation step using the catalyst comprising the molecular sieve has also been identified as a preferred process to prepare the base oil to be used in the present invention. More preferred the first and second hydroisomerisation steps are performed in series flow.

In step (a) the feed is contacted with hydrogen in the presence of the catalyst at elevated temperature and pressure. The temperatures typically will be in the range of from 175 to 380° C., preferably higher than 250° C. and more preferably from 300 to 370° C. The pressure will typically be in the range of from 10 to 250 bar and preferably between 20 and 80 bar. Hydrogen may be supplied at a gas hourly space velocity of from 100 to 10000 Nl/l/hr, preferably from 500 to 5000 Nl/l/hr. The hydrocarbon feed may be provided at a weight hourly space velocity of from 0.1 to 5 kg/l/hr, preferably higher than 0.5 kg/l/hr and more preferably lower than 2 kg/l/hr. The ratio of hydrogen to hydrocarbon feed may range from 100 to 5000 Nl/kg and is preferably from 250 to 2500 Nl/kg.

The conversion in step (a) as defined as the weight percentage of the feed boiling above 370° C. which reacts per pass to a fraction boiling below 370° C., is at least 20 wt %, preferably at least 25 wt %, but preferably not more than 80 wt %, more preferably not more than 65 wt %. The feed as used above in the definition is the total hydrocarbon feed fed to step (a), thus also any optional recycle of a high boiling fraction which may be obtained in step (b).

In step (b) a residue is isolated from the product of step (a). With a residue is here meant that the most highest boiling compounds as present in the effluent of step (a) are part of the residue. Distillation may be performed at atmospheric pressure as illustrated in WO-A-02/070627 or lower as illustrated in WO-A-2004/007647.

Step (c) may be performed by means of solvent or catalytic dewaxing. Solvent dewaxing is advantageous because a haze free paraffin oil may then be obtained as for example described in WO-A-0246333. A haze free base oil is defined as a composition having a cloud point of below 15° C. A hazy paraffin base oil has a cloud point of 15° C. and above. Catalytic dewaxing may yield a hazy paraffin base oil as is illustrated in WO-A-2004/033595 and 2004/0065588. Catalytic dewaxing is however preferred over solvent dewaxing due to its simpler operation. Processes have therefore been developed to remove the haze from a hazy paraffinic base oil as obtained by catalytic dewaxing. Examples of said processes are U.S. Pat. No. 6,051,129, US-A-2003/0075477 and U.S. Pat. No. 6,468,417. Applicants now found that when a hazy paraffin base oil as prepared by catalytic dewaxing is used to prepare the blended oil a clear and bright product is obtained. Thus a very interesting use is found for such a hazy paraffin base oil as obtained from a Fischer-Tropsch wax.

Dewaxing is preferably performed by catalytic dewaxing. Catalytic dewaxing is well known to the skilled reader and is suitably performed in the presence of hydrogen and a suitable heterogeneous catalysts comprising a molecular sieve and optionally in combination with a metal having a hydrogenation function, such as the Group VIII metals. Molecular sieves, and more suitably intermediate pore size zeolites, have shown a good catalytic ability to reduce the pour point of a base oil precursor fraction under catalytic dewaxing conditions. Preferably the intermediate pore size zeolites have a pore diameter of between 0.35 and 0.8 nm. Suitable intermediate pore size zeolites are mordenite, ZSM-5, ZSM-12, ZSM-22, ZSM-23, SSZ-32, ZSM-35 and ZSM-48. Another preferred group of molecular sieves are the silica-aluminaphosphate (SAPO) materials of which SAPO-11 is most preferred as for example described in U.S. Pat. No. 4,859,311. ZSM-5 may optionally be used in its HZSM-5 form in the absence of any Group VIII metal. The other molecular sieves are preferably used in combination with an added Group VIII metal. Suitable Group VIII metals are nickel, cobalt, platinum and palladium. Examples of possible combinations are Ni/ZSM-5, Pt/ZSM-23, Pd/ZSM-23, Pt/ZSM-48 and Pt/SAPO-11. Further details and examples of suitable molecular sieves and dewaxing conditions are for example described in WO-A-9718278, U.S. Pat. No. 5,053,373, U.S. Pat. No. 5,252,527, U.S. Pat. No. 4,574,043, U.S. Pat. No. 5,157,191, WO-A-0029511, EP-A-832171.

Catalytic dewaxing conditions are known in the art and typically involve operating temperatures in the range of from 200 to 500° C., suitably from 250 to 400° C., hydrogen pressures in the range of from 10 to 200 bar, preferably from 40 to 70 bar, weight hourly space velocities (WHSV) in the range of from 0.1 to 10 kg of oil per litre of catalyst per hour (kg/l/hr), suitably from 0.2 to 5 kg/l/hr, more suitably from 0.5 to 3 kg/l/hr and hydrogen to oil ratios in the range of from 100 to 2,000 litres of hydrogen per litre of oil.

From the effluent of step (c) the desired paraffinic base oil having the required viscosity made be directly obtained. If required any lower boiling compounds may be removed in a step (d) by distillation such to meet said viscosity requirements as specified above.

Applicants also found that it is possible to use a hazy paraffinic base oil as described above. It has been found that a clear oil blend is obtained when the blending involving the hazy paraffinic base oil is performed at a temperature of greater than 50° C.

The oil blends according to the invention can advantageously be used as process oils wherein today various existing process oils such as TDAE (treated distillate aromatic extract), naphthenic and paraffinic process oils are employed.

The oil blends according to the invention can be widely used as extender oil in rubber formulations (e.g. tyres and other automotive and technical rubber articles), rubber mould articles and seals. Applicants found that in particular blends containing a hazy paraffin base oil component as described above permitted to eliminate the use of microcrystalline wax additives that were required otherwise, while the low-temperature performance of the extended rubber article thus obtained was improved. Rubber extender oil is added to natural and synthetic rubbers for a number of reasons, for example to reduce the mixing temperature required during processing and to prevent the scorching of the rubber polymer when it is being ground, to decrease the viscosity of the rubber to improve the general workability of the rubber compound, to aid in the dispersion of fillers, to modify the physical properties of the rubber compound, and for other reasons. Generally, the oil used in rubber extender applications has been a mineral oil composition comprising a high concentration of aromatic components with high viscosity, low volatility and high solvency for the rubber compound. Rubber extender oil compositions having greater than 3 wt. % (IP346) polynuclear aromatics are classified as “carcinogenic” according to the European legislation (EU Substance Directive 67/548/EEC) and must be labeled with the risk phrase “R45” (may cause cancer) and the label “T” (toxic, skull and crossbones) in Europe. From the viewpoint of health, safety and environmental impact, it is desired to produce an alternative to distillate aromatic extracts for use as a rubber extender oil composition, which contains at most 3 wt. % (IP346) polynuclear aromatics, and Therefore has low carcinogenicity. The use of rubber extender oil compositions having a polynuclear aromatics content of at most 3 wt. % (IP346) in the production of automotive tires is of special importance, since PNAs are released into the environment in significantly higher quantities due to tire wear compared with that found in the exhaust gas produced by modern passenger cars. There is therefore a need for a replacement rubber extender oil composition having at most 3 wt. % PNA (IP346), wherein the properties of the rubber extender oil composition are such that major reformulation of the rubber compounds used in automotive tires is not required. This is the more relevant, since tyre material is distributed into the environment due to abrasion by road surfaces. The EU Directive 76/769/EEC for tyres thus specifies that tyre rubber compositions may not contain more than 1 mg/kg Benzo[a)pyrene, and at most 10 mg/kg of the sum of the following Polycyclic Aromatic Hydrocarbons (PAH): Benzo [a]anthracene, Chrysene, Benzo[b]fluoranthene, Benzo[b]fluorantheneBenzo[j]fluoranthene, Benzo[k]fluorantheneBenzo[a]pyrene, Benzo[e]pyrene and Dibenz(a,h)anthracene. This has been achieved by using the oil blends according to the present invention, while tyre rubbers could be formulated having good properties.

The rubber extender oil composition produced by the process of the present invention may be used in synthetic rubbers, natural rubber and mixtures thereof. Examples of synthetic rubbers for which the rubber extender oil composition produced by the process of the present invention is suitable for include, but is not limited to, styrene-butadiene copolymers (SBR), polybutadiene (BR), polyisoprene (IR), polychloroprene (CR), ethylene-propylene-diene ternary copolymers (EPDM), acrylonitrile-butadiene rubber (NBR) and butyl rubber (IIR).

Accordingly, the invention preferably relates a rubber composition comprising

-   -   a) at least one rubber, rubber component, or mixtures thereof,     -   b) a rubber extender oil composition produced by the process of         the present invention in the range of from 0.5 wt. % to 50 wt. %         based on the weight of the rubber composition, and optionally at         least one component selected from:     -   c) reinforcing agents,     -   d) cross-linking agents and/or cross—linking auxiliaries,     -   e) inorganic fillers, and     -   f) waxes and/or antioxidants.

The present invention further relates a to shaped rubber articles comprising the oil blends and extended polymers.

Furthermore, the present invention also provides for use of the oil blends as kneader oil in bunberry mixers, as carrier oil in printing inks, and as carrier oil for additives, as a sand binder for metal casting, as a process oil in the production of carbon black for printing inks, as a process oil in electrical wire and cable insulating materials and as dust binder oils.

Although the Dao and/or DACO in the blends according to the present invention may be dewaxed in a separate dewaxing step, in a preferred aspect of the present invention, a blend of the aromatic extract or the de-asphalted oil and the paraffin base oil component or a paraffin base oil precursor component may be subjected to a solvent or catalytic dewaxing dewaxed step to obtain the brightstock blend. The invention accordingly preferably relates to a process to prepare an oil blend according to the invention, which process further comprises an additional step of performing a solvent dewaxing step to the blend obtained in step (iii), or to a mixture blend of the de-asphalted oil obtained in (i) and/or the aromatic extract obtained in (ii) with the paraffin base oil precursor component to obtain a dewaxed oil blend. The thus obtained blend has a higher viscosity index.

The paraffin base oil precursor component is preferably obtained from a Fischer-Tropsch wax by a process involving steps (a) and (b). The residue obtained in (b) may have been partly dewaxed in order to make the precursor material easier to handle in transport and to increase its heavy oil content. Preferably the paraffin base oil precursor material has a pour point of between 0 and 100° C., more preferably between 20 and 60° C.

Applicants have further found that particular dewaxed oil blends comprising a paraffinic base oil component and more than 40 wt % of a mineral derived residual and de-asphalted oil component (DAO and/or DACO) have advantageous viscometric properties in cylinder oil lubricants for use in cross-head engines and trunk piston engines. The dewaxing treatment not only makes the blend particularly suitable as part of a cylinder oil composition lubricant oil blend for marine engines due to the increased viscosity index, but also advantageously provide for a bright stock type product without the requirement to perform separate dewaxing steps for the components. Cylinder oil compositions are preferably used on a once-through basis by means of injection devices that apply the cylinder oil to lubricators positioned around the cylinder liner of a slow speed diesel engine. Diesel engines may generally be classified as slow-speed, medium-speed or high-speed engines, with the slow-speed variety being used for the largest, deep draft vessels and in industrial applications. Slow-speed diesel engines are typically direct coupled, direct reversing, two-stroke cycle engines operating in the range of about 57 to 250 rpm and usually run on residual fuels. These engines are of crosshead construction with a diaphragm and stuffing boxes separating the power cylinders from the crankcase to prevent combustion products from entering the crankcase and mixing with the crankcase oil. Medium-speed engines typically operate in the range of 250 to about 1100 rpm and may operate on the four-stroke or two-stroke cycle. These engines typically are of trunk piston design, and many operate on residual fuel as well. They may also operate on distillate fuel containing little or no residua. On deep-sea vessels these engines may be used for propulsion, ancillary applications or both. Slow speed and medium speed marine diesel engines are also extensively used in power plant operations. The present invention is applicable to them as well. Each type of diesel engine employs lubricating oils to lubricate piston rings, cylinder liners, bearings for crank shafts and connecting rods, valve train mechanisms including cams and valve lifters, among other moving members. The lubricant prevents component wear, removes heat, neutralizes and disperses combustion products, prevents rust and corrosion, and prevents sludge formation or deposits. In low-speed marine crosshead diesel engines, the cylinders and crankcase are lubricated separately, with cylinder lubrication being provided on a once-through basis by means of injection devices that apply cylinder oil to lubricators positioned around the cylinder liner. This is known as an “all-loss” lubrication system. The cylinder oil is typically formulated to provide for good oxidation and thermal stability, water demulsability, corrosion protection and good antifoam performance. Alkaline detergent additives are also present to neutralize acids formed during the combustion process. Dispersant, antioxidant, antifoam, antiwear and extreme pressure (EP) performance may also be provided by the use of suitable additives.

A cylinder oil according to the present invention comprises (i) the DAO and/or DACO blend, the paraffin base oil component and (ii) one or more additives selected from dispersants, overbased detergents, antiwear agents, friction reducing agents, viscosity improvers, viscosity thickeners, metal passivators, acid sequestering agents and antioxidants. More preferably all of the listed additives are present. Examples of such additives are for example described in U.S. Pat. No. 6,596,673, which publication is hereby incorporated by reference. The presence of the haze in the hazy paraffinic oil as described above, especially when also overbased detergents are present in the cylinder oil formulation, surprisingly gave cylinder oils with highly improved liner wear performance. The presence of such a paraffinic oil component, optionally as part of the brightstock blend, will provide the cylinder oil with a high viscosity index. The high VI will give the added benefit of easier pumping from the lubricant oil tank under low temperature conditions, as well as a higher oil film thickness under high temperature operating conditions within the cylinder, compared to the analogous all-mineral lower VI formulations.

The invention will be illustrated by the following non-limiting examples.

EXAMPLE 1

Oil blends A-D were made using the ease oils listed in Table 1. All blends were clear and bright at room temperature (20° C.). The properties of the blends are listed in Table 3.

TABLE 1 Kinematic Kinematic viscosity viscosity Pour Cloud at 100° C. at 40° C. Point Point Appear- (mm²/sec) (mm²/sec) VI (° C.) (° C.) ance Dewaxed 52.54 1390.7 79 −6 −9 DAO DACO 60 3300 15 15 Hazy 13.47 92.0 147 −9 >20 Hazy Paraffin base oil Non-hazy 16.32 120.6 145.4 −42 −14 Clear paraffin and base oil bright (*) the oil showed a haze at ambient conditions

The dewaxed DAO of Table 1 was obtained from Shell Nederland Verkoop Maatschappij BV as its commercial product listed “MVIP 1300”. This product was prepared by subjecting a residual crude petroleum fraction to a propane de-asphalting step followed by solvent dewaxing using (50 vol %/50 vol %) methyl-ethylketone.

The hazy paraffin base oils of Table 1 were obtained by the following process. From a hydroisomerised Fischer-Tropsch wax a distillation residue was isolated having the properties as listed in Table 2.

TABLE 2 Feed to catalytic dewaxing Congealing Point ° C. 71 IBP % m distilled ° C. 302 10 ° C. 402 50 ° C. 548 70 ° C. 613 90 ° C. 706 FBP ° C. >720

The above residue was contacted with a dewaxing catalyst consisting of 0.7 wt % platinum, 25 wt % ZSM-12 and a silica binder. The dewaxing conditions were 40 bar hydrogen, WHSV=1 kg/l.h, and a hydrogen gas rate of 500 Nl/kg feed. The experiment was carried out at 300 and 323° C. From the effluent a residue boiling above 490° C. was isolated to obtain a hazy base oil of Table 1. The oil obtained at 325° C. was subjected to a solvent dewaxing at −20° C. The solvent was a 50 vol % methyl ethylketone and 50 vol % toluene to obtain the clear and bright base oil of Table 1.

Table 3 shows properties of blends according to the invention:

TABLE 3 Blend A B C D E F Content of 69 63 75 70 — — Dewaxed DAO (wt %) Content of DACO — — — — 45 45 (wt %) Content of Hazy 31 — 25 — 55 — paraffin base oil (wt %) Content of Non- — 37 — 30 — 55 hazy paraffin base oil (wt %) Kinematic 28.6 28.1 31.59 31.86 22.6 25.0 viscosity at 100° C. (mm²/sec) Viscosity index 100 103 95 97 96 95 Pour point (° C.) −9 −12 −2 −4 +6 +6 Cloud point — −19 14 −4 — — (° C.) Polar compounds 51.8 47.4 56.2 52.5 (wt %)

In Table 4, further blend compositions according to the invention were calculated and compared with commercially available conventional process oils (Gravex and Catenex are trademarks of Shell).

TABLE 4 Examples Comparative Comparative Comparative Example I Example H Example H Paraffinic Paraffinic Comparative Naphthenic Process Oil Process Oil Example G Process Oil Catenex S Catenex H DACO GTL G (TDAE) H Gravex 985 I 579 J 779 DACO 80 60 50 40 GTL 20 40 50 60 Density @ 15° C. [kg/m3] 980 837 952 939 923 926 909 905 895 895 Sulphur [% m] 4 <0.001 3.2 2.8 2.4 0.9 2 1.3 1.6 0.05 Pour Point [° C.] 15 −24 6 27 0 −12 −3 −9 −9 −9 Kinematic Viscosity @ 3300 491 1298 210 633 700 468 500 357 480 40° C. [mm2/s] Kinematic Viscosity @ 60 19 43.5 14.5 33.5 26 29.9 32 26.9 31 100° C. [mm2/s] Viscosity Index 15 142 57 51 82 20 92 95 101 94 Viscosity Gravity 0.916 0.741 0.879 0.880 0.843 0.848 0.825 0.819 0.808 0.804 Constant [DIN 51378] Examples Comparative Comparative Comparative Comparative Example H Example I Example H Example G Naphthenic Paraffinic Paraffinic DACO GTL G (TDAE) H Process Oil I Process Oil J Process Oil EU Directive 76/769/EEC for tyres Benzo[a)pyrene: max. 1 mg/kg 0.18 <0.1 [mg/kg] Sum of the following Polycyclic 3 <1 Aromatic Hydrocarbons (PAH): max. 10 mg/kg Benzo [a]anthracene, Chrysene, Benzo[b]fluoranthene Benzo[b]fluoranthene Benzo[j]fluoranthene, Benzo[k]fluoranthene Benzo[a]pyrene, Benzo[e]pyrene, Dibenz(a,h)anthracene. [mg/kg]

The blends according to the invention all met the requirements set out by EU Directive 76/769/EEC for rubber extender oils in tyre applications. 

1. A process to prepare an oil blend comprising: (i) de-asphalting a mineral-derived vacuum residue to obtain a de-asphalted oil, (ii) blending the de-asphalted oil obtained in (i) with a paraffin base oil, wherein the paraffin base oil is prepared by oligomerisation of lower molecular weight olefins to iso-paraffins having the desired viscosity, or by hydroisomerisation of a paraffin wax as prepared in a Fischer-Tropsch synthesis step, and dewaxing a residual fraction as separated from the effluent of said hydroisomerisation process.
 2. The process according to claim 1, further comprising performing a solvent dewaxing step to the blend obtained in step (ii), to obtain a dewaxed oil blend.
 3. An oil blend obtained by the process according to claim 1, comprising a paraffin base oil component and more than 40 wt % of a mineral derived residual and de-asphalted oil component.
 4. An oil blend according to claim 3, wherein the blend has a kinematic viscosity at 100° C. of greater than 25 mm²/sec.
 5. An oil blend according to claim 3, wherein the blend has a kinematic viscosity at 100° C. of less than 40 mm²/sec.
 6. An oil blend according to claim 3, wherein the paraffin base oil component has a viscosity at 100° C. of from 8 to 25 mm²/sec
 7. An oil blend according to claim 3, wherein the mineral derived residual and de-asphalted oil component has a pour point of below −3° C., a viscosity index of between 70 and 85 and a polar compounds content of between 60 and 80 wt % by IP
 368. 8. An oil blend according to claim 3, wherein the paraffinic base oil component has a viscosity index of between 125 and
 180. 9. An oil blend according to claim 3, wherein the content of polar compounds in the blend is below 60 wt % by IP
 368. 10. An oil blend according to claim 3, wherein the difference in cloud point and pour point of the paraffin base oil component is greater than 25° C. and wherein the difference in cloud point and pour point of the base oil blend is smaller than 25° C.
 11. A cylinder oil formulation for use as total loss lubricant in slow speed engines comprising (i) the blend obtainable according to the process of claim 1, and (ii) one or more additives selected from the group consisting of dispersants, overbased detergents, antiwear agents, friction reducing agents, viscosity improvers, viscosity thickeners, metal passivators, acid sequestering agents and antioxidants.
 12. The cylinder oil according to claim 11, wherein the oil comprises an overbased detergent and wherein the kinematic viscosity at 100° C. of the cylinder oil formulation is between 12 and 22 mm²/sec.
 13. A rubber composition comprising: a) at least one rubber, rubber component, or mixtures thereof, b) an oil blend according to claim 3, in the range of from 0.5 wt. % to 50 wt. % based on the weight of the rubber composition, and optionally at least one component selected from the group consisting of: c) reinforcing agents, d) cross-linking agents and/or cross-linking auxiliaries, e) inorganic fillers, and f) waxes and/or antioxidants.
 14. A shaped article of an extended rubber according to claim
 13. 15. (canceled)
 16. A process to prepare an oil blend comprising: (i) de-asphalting a mineral-derived vacuum residue to obtain a de-asphalted oil, (ii) extracting from the de-asphalted oil an aromatic extract by solvent extraction process; and (iii) blending the aromatic extract obtained in (ii) with a paraffin base oil, wherein the paraffin base oil is prepared by oligomerisation of lower molecular weight olefins to iso-paraffins having the desired viscosity, or by hydroisomerisation of a paraffin wax as prepared in a Fischer-Tropsch synthesis step, and dewaxing a residual fraction as separated from the effluent of said hydroisomerisation process. 